carson



3 Sheets-Sheet 1.

(Ne Model.)

w W CARSON MOLE, BIKE, OR DAM FOR SILT BEARING STREAMS.

Patented July 5, 1892.

' Ill/VENTOR (No Model.) 3 SheetsSheet 2.

W. W.. CARSON. MOLE, DIKE, 0R DAM FOR. SILT BEARING STREAMS.

No.- 478,154. Patented July 5, 1892;

FIG. 5.

z. zz/l) FIG. "1..

. (No Model.)

{Sheets-Sheet 3. w. W. CARSON. MOLE, DIKE, 0R DAM FDR SILT BEARING STREAMS. NO. 478,154.

Patented July 5, 1892.

WITNESSES: lllll/E/VTO/P UNITED STATES PATENT OFFICE.

WILLIAM IVALLER CARSON, OF KNOXVILLE, TENNESSEE.

MOLE, D|KE,'OR DAM FOR SILT-BEARING STREAMS.

SPECIFICATION forming part of Letters Patent No. 478,154, dated July 5, 1892. v

, Application filed July 24, 1891.

To all whom, it may concern:

Be it known that I, WILLIAM WALLER OAR- SON, a citizen of the United States, residing at Knoxville, in the county of Knox and State of Tennessee, have invented a new-and useful Device for Building aMole, Dike, or Dam in a Silt-Bearing Stream, where the office of such mole, vdike, or dam is to reduce the width of the stream, to direct or control its flow, and to prevent the scour of its bed or the caving of its banks; and I do hereby declare that the following is a full, clear, and exact description of my invention, which will enable others skilled in the art to which it appertain's to make and use the same.

To carry my invention into effect I build the dike as far as possible while' the current is comparatively feeble. I build a number of hollow wooden molds or shells. I weight these heavily enough to enable them to resist any effort which this feeble current may make to move them. I sink these in such numbers and places as the shape, dimensions, and position of the proposed dam may require. These molds or shells gather silt from the stream into their cavities, and thus mold it into blocks, and these blocks of silt, inoased in their wooden shells, together with the mass of silt which by obstructing the current they cause the stream to deposit about them and to their rear, compose the dike. It is evident that one of these shells thus filled with silt and surrounded by silt can be made capable to resist the effort of any given current to move it by simply making its length, measured in the direction of the current, sufficiently great. Thus in designing a dike to stand in a current of given maximum velocity any desired factor of safety can be given it by making the shells sufficiently long. This is one of the great advantages of my invention. My invention is the hollow wooden mold or shell, whose use has just been de scribed. For thelack of a better name I shall call it a caisson. The economical dimensions for the caisson will depend on the velocity of the maximum current, the price of lumber, the kind of sinking material used, and on a number of other things.

depth of ten (10) or twelve (12) feet, with a breadth about equal to its depth will prob- A length of between fifty and seventy (70) feet, a

Serial No. 400,658. (No model.)

ably give the most satisfactory results, as a general thing. The caisson must be made strong enough to resist the bending movements and the crushing and shearing stresses that may be caused by the current or by any superincumbent weight or by the enormous weight of the materialthat may be used to sink it. Hence it is evident that with the dimensions mentioned above the caisson must be strongly built; but it is exceedingly desirable in order to reduce both the cost and the buoyancy of the caisson to use as little wood as possible in its construction. I therefore give it the requisite strength, while economizing material, by making each face (including bottom and top) a truss of some kind. Any kind of truss maybe used, provided the Webbing is close enough to prevent the deposited silt frombeing washed out again. Thus the trusses of a caisson which is to be surrounded by other caissons may be made very open to economize lumber; but the form of truss which I consider best adapted to general use consists of a pair of chords connected by parallel-web members of plank, which last are placed as close together as may be necessary to prevent the washing away of the deposited silt. This form of truss is very similar in appearance to a plate-girder. Its wall may be more or less open, especially toward its downstream end, and may be strengthened laterally by posts, ties, stringers, &c., whenever the pressure of the silt demands it. Swaybraces between the trusses of the caisson give lateral stiffness, just as in a deck-bridge. Indeed, the caisson is strikingly like a bridge. I make the fastenings of wood. I use a few iron bolts, however, to take the temporary stresses developed while sinking. After the caisson is once in position these may rust away without harm. The material used to sink the caisson may be applied in any manner whatever; butI decidedly prefer to lace it in one or more cages or chambers specially constructed to receive it. I prefer a'single cage, and I place that at or near the upstream end of the caisson. This allows the current to sweep the lighter end around, and thus to keep the caisson headed in the proper direction while it fills and surrounds itself with silt. I

The accompanying drawings, in which similar letters of reference refer to similar parts throughout, show the manner of using the caissons and give views of two of them built the one with open the other with closed trusses. Both have the separate cage at the end for sinking material.

Figure 1 givesa general view of the caisson built with the open-truss style of faces. A is the-cage or chamber to contain stone, earth, or other material needed to sink the caisson.

Figs. 2 to 7, inclusive, refer to the caisson built with the plate-girder style of faces. Fig. 4 shows the general appearance of this style of caisson. A is the side and P is the front of the cage for sinking material. L is the plate or wall of wood which, with the chords 0 N, composes avertical plate-girder. D D are sway-braces. Fig. 2 gives a view from above, on a larger scale, of a portion (say in the vicinity of O in Fig.4) of a horizontal plate-girder truss. Fig. 3 gives a side view, to the same scale of the corresponding portion, of a vertical truss. Fig. 5 shows a cross-section of the caisson on the line T V. Fig. 6 shows a portion of this same cross-section. Fig. 7 shows a portion of a cross-section on X Y. Figs. 6 and 7 are drawn to a larger scale, so as to show how the planks F H, 850., composing the wall of a horizontal truss, the planks E K, 850., composing the walls of a vertical truss, and the four timbers composing a chord may be interlocked and pinned together. Thus in Figs. 2 and 6 a vertical pin may be seen connectin g two pieces of the chord and the plank -F together. In Figs. 3 and 6 two horizontal pins may be seen, each connecting two pieces of the chord and the plank E together. Similarly in Figs. 2, 3, and 7 may be seen a hori zontal pin connecting two pieces of the chord and the plank K together and two vertical pins, each connecting two pieces of the chord and the plank II together.

Fig. 8 gives (with sway-braces omitted) a front or rear View, partly in section, of the cage for sinking material.

Fig. 9 gives a side elevation of three of the caissons in position with the deposit of silt in their rear.

Fig. 10 shows a vertical section of a dike or part of a dike, taken at right angles to the current. The caissons would generally be closer together, however, than the figure indicates.

Fig. 11 gives a top view of this same dike or part of a dike. The arrows fly with the current.

It is obvious that the water must be allowed to pass through the caisson, but with diminished velocity, in order that the caisson may gather silt into its cavity. The open style of truss shown in Fig. 1 will evidently give ready access to the water, and the obstruction offered to the flow by the cage, the chords, and the braces will reduce the current suflicientl y to allow the deposit of silt to occur within and about the caisson. \Vhere the plategirder style of truss shown in Fig. 4 is used,

the water may be allowed to enter the cavity by passin' g directly through the cage, provided stone is used for sinking; but where earth is used for sinking this would be inadmissible, for the cage must evidently be tight enough to confine the sinking material used. In such cases a plank or two may be omitted from the wall just behind the cage to admit the water, or the wall itself may be built more or less open, as already suggested. It is evident that the cavity or mold of the caisson may be subdivided into as many smaller cavities as may be desired; but I think nothing would be gained by doing this. Special attention is called to two points whichI consider highly advantageous. I put the weight which sinks the caisson at or near its upstream end, as already pointed out, and I put the smallest cross-section of the caisson approximately at right angles to the current, so as to reduce to a minimum the tendency of the current to move it. I make the caissons of quadrangular cross-section-that is, of four trusses. It is evident that any other cross-section 0r number of trusses could be used, but not, I think, with economy.

A reference to Fig. 10 shows that the caisson is intended to act not only as a mold to gather silt within it, but also as a core to gather silt around it. Moreover, certain planks, as E H, &c., are seen in Figs. 2 to 7, inclusive, to project beyond the chords. These projections obstruct the current and help to induce the deposit of silt around and about the caisson. The lengths of these projecting ends can be increased by lengthening these planks or by placing the chords closer together. Thus the core-like action of the caisson can be made more prominent or its moldlike action less so, either or both. As an extreme case some of the walls and some of the chords can be omitted from behind the cage, thus leaving the downstream end of the caisson entirely open and reducing it to one or more simple cores.

In order to make practical use of my inven tion, (especially where the aim is to prevent scour or to protect a caving bank,) a series of dikes, each projecting, as shown, into or across the stream, will generally be needed. In cases where no caving can be tolerated the dikes will be placed very close together; but in cases where it is only necessaryto hold the general course of the stream and where a limited amount of caving between the dikes may be admitted they may be placed several hundred feet apart.

Having thus fully described my invention, What I claim, and desire to secure by Letters Patent, is-

1. A hollow weighted wooden caisson having trusses for faces, as described, and for the purpose set forth.

2. A weighted wooden caisson built with one or more chambers to receive deposits of silt and with trusses for faces, as described, and for the purpose set forth.

3. A wooden caisson built with one or more chambers'to contain material to sink it and with trusses for faces, as described; and for the purpose set forth.

4. A wooden caisson built with one or more chambers to contain material to sink it and one or more internal cavities to receive deposits of silt, as described, and for the purpose set forth.

5. A wooden caisson weighted at or near one end and of such shape that its smallest cross-section shall be approximately at right angles to the currentwhen the weighted end of the caisson is placed upstream, as described, and for the purpose set forth.

6. A wooden caisson consisting of one or more chambers to contain material to sink it and one or more projecting cores for 'silt to gather around and about, as described, and

for the purpose set forth.

7.' An elongated hollow wooden caisson of hedral angles mentioned above and alongside of each other to lie along and about the line of intersection of the aforesaid faces; (0) a wooden pin to connect together two of the chord-stringers with the face-piece which passes between them, all substantially as described, and forthe purpose set forth.

WILLIAM WALLER CARSON.

Witnesses:

J. W. S. FRIERSON, R. L. TEASDALE. 

